4 
COI.ORADO Experiment Station 
from the east. At one g-eologic period the Valley was the bed of 
a lake, and all except the recently formed soils were deposited by 
the waters of this lake. Streams flowing into the lake were laden 
with this material and deposited it in fan-shaped deltas spreading 
outward from their canons. Except in a few cases these fans are 
not apparent to the eye, and the Valley appears to be a flat, treeless 
plain. The streams flowing into the Valley from the west being 
larger, but carrying less heavy material, formed deltas more ex¬ 
tensive and flatter than those deposited on the eastern side, with 
the result that the trough of the Valley is considerably east of its 
north and south axis. Most of the large irrigation systems are 
located on this western slope. Here the inclination of the land 
varies from 5 to 30 feet per mile except near the foothills, and is 
so uniform that canals are usually constructed along section lines 
either east or north. The Prairie Ditch runs foi* over 25 miles in 
a straight line, and it is reported that at no point was an excava¬ 
tion of more than two feet necessary. 
The elevation of the Valley is high, its lowest point being over 
7,500 feet above sea level. Practically all of the farming land is at 
an elevation between 7,500 and 8,500 feet. Elevations of some of 
the principal towns are given below. 
Town. 
Elevation. 
Town. 
Elevation. 
Villa Grove . 
.7,962 ft. 
Del Norte. 
.7,868 ft. 
Sag'uache . 
.7.740 ft. 
Monte Vista . 
.7.650 ft. 
Crestone .. 
.7,871 ft. 
Alamosa . 
.7.536 ft. 
Mo'ffat . 
.7.568 ft. 
P)lanca . 
.8,403 ft. 
Hooper . 
.7^566 ft. 
La Tara. 
.7.597 ft. 
Mosca . 
.7.562 ft. 
Manassa .. 
.7,660 ft. 
San Acacio. 
.7.737 ft- 
Capulin . 
.7,800 ft. 
[arosa . 
.7.650 ft. 
CLIMATE. 
The climate is characterized by almost continuous sunshine, 
very little rainfall, extremes of temperature, and a high wind move¬ 
ment. The mean annual precipitation is between 8 and 9 inches, 
varying widely from season to season and at different points, the 
highest recorded being 18.85 hiches at San Luis in 1891, and the 
lowest 2.88 inches at Saguache in 1896. The heaviest rainfall of 
the year occurs in July and August at the time when most needed. 
Usually the rains are of little Jirect benefit to growing crops, but 
the streams flooded from rains in the hills afford water for irriga¬ 
tion for a few days. 
